Test added for inverted file names;  INVERT_TARGET simple logic and
test.
Run test data through picard-tools-1.72/FixMateInformation after hand
editing: note that the * Y and Y * cases are changed to Y Y, but flags
remain correct for unaligned.  20 Y and Y 20 are not changed by
FixMateInformation.
Experiments with a different approach to INVERT_TARGET, tests passing.
Tests for EXCLUDE_UNALIGNED set to true for xahuman data (failing) and 
the reversed filenames for yhuman (failing) for historical reference.